High Dose Warfarin Requirement in a Girl with Polymorphisms in VKORC1 Gene

บทคัดย่อ

Abstract:

Warfarin, a vitamin K antagonist, has been commonly used as long term anticoagulant in adult and children
with  thrombosis. The dose requirement of warfarin is determined by the concomitant drugs, age, diet, and genetic
factors. The genetic factors that related to the warfarin dosage are CYP2C9, a warfarin metabolism enzyme, and
VKORC1,  a target enzyme of warfarin. We reported the etiology of high dose warfarin requirement in a-15-year old
girl,  underlying ulcerative colitis, with recurrent thrombosis. Warfarin dosage requirement was range of 42-68.3 mg/
week  (0.2-0.3 mg/kg/day) in order to maintain target INR at 2-3. The genetic polymorphisms of VKORC1 were identified
 and corresponded to haplotype 7. This haplotype was able to explain the high dose warfarin requirement.